Investigation of the Condensation of Boron Oxide in a HC-Boron Gel-Fuel Ramjet

Shachar Balas
Work towards M.Sc. degree under the supervision of Prof. B. Natan
Department of Aerospace Engineering
Technion – Israel Institute of Technology

The ramjet engine is a very attractive propulsion system because of its high specific impulse compared to rockets and its relative simplicity compared to other air-breathing devices.
The use of gel fuels increases safety and improves the energetic performance of the engine since it allows the addition of metal particles to the hydrocarbon fuels.
Boron exhibits remarkable theoretical energetic performance with the highest energy density of all elements.  One of the main combustion products is boron oxide, B2O3, which has a latent heat of vaporization of 366.5 kJ/mol. The realization of the full energetic potential of boron lies on the condensation of the boron oxide formed during burning.
This work focuses on increasing the energetic performance of a Hydrocarbon-Boron Gel Fuel Ramjet by condensing boron combustion products, using a two-stage combustor. With an adequately high bypass ratio, the addition of cold bypass air to the combustion products cools the mixture below the boron oxide boiling point, leading to the condensation of the boron oxide and consequently to the release of the latent heat of vaporization stored in its gaseous form. The condensation process was examined using three different theoretical models for nucleation of B2O3 on solid particles in the flow. The effect of the mixing chamber geometry and the bypass air injection characteristics on the of the mixing process, which affects the time required for completing the condensation process was investigated.
Using CFD tools and a dedicated code, the behavior and properties of the mixing process were simulated in the after-mixing chamber, obtaining the residence time required for the completion of condensation.

The talk will be given in Hebrew

Wed, 12-11-2014, 16:30 (Gathering at 16:00)

Classroom, ground floor, Library, Aerospace Eng.

Light refreshments will be served before the lecture

Investigation of the Condensation of Boron Oxide in a HC-Boron Gel-Fuel Ramjet